The present invention relates to a surveying instrument employing a sighting telescope having an auto-focusing function.
Conventionally, a surveying instrument such as an electric distance meter, and an electronic theodolite have been known. The distance meter is for measuring a distance to an aiming point, and the theodolite, or an angle measuring instrument is for measuring horizontal and vertical (elevational) angles between a reference point and an aiming point.
In such a surveying instrument, a sighting telescope is provided for accurately sighting the instrument on an aiming point. By aligning the sighting telescope so that the aiming point is located at the center of field of view, the axis of distance measuring or measuring the horizontal and elevational angles is aligned to intersect the aiming point.
Recently, a total station, which has functions of both the distance measuring instrument and the angle measuring instrument, has been generally used. In the total station, both the distance and the angles (horizontal and elevational angles) of the aiming point are measured at a time by directing the sighting telescope to the aiming point.
In order to view the aiming point clearly within the field of view of the sighting telescope, a focusing mechanism is provided. The focusing mechanism is to be manipulated so that an in-focus image of the aiming point is formed. To ease the focusing operation, recently, sighting telescopes having an auto-focusing function have been employed in the surveying instruments.
With the auto-focusing function, the focusing condition of the sighting telescope is automatically adjusted. Thus, the auto-focusing function makes the operator free from troublesome manipulation of focusing mechanism, and allows the operator to concentrate on centering the aiming point in the field of view of the sighting telescope.
In such a conventional sighting telescope, however, the operator is required to manually operate a switch for actuating the auto-focusing function when the auto-focusing operation is to be executed. To operate the switch when the sighting telescope is being aligned (moved) is bothersome. Further, the operator may push a wrong button by mistake, or the operator may unintentionally turn the telescope by pushing the switch too hard.
It is therefore, an object of the present invention to provide an improved surveying instrument provided with a sighting telescope having an auto-focusing function which is easy to operate.
For the above object, according to the present invention, there is provided a surveying instrument, which includes: a telescope utilized for sighting at an aiming point; an auto-focusing system that executes an auto-focusing operation for automatically adjusting focusing condition of the telescope; a supporting member that movably supports the telescope; a movement detection system that detects moving status of the telescope; and a controlling system that controls the auto-focusing system to perform the auto-focusing operation in accordance with a moving status of the telescope.
With this constitution, since the auto-focusing system is operated automatically, operability of the surveying instrument is improved, without the defects of the prior art. Thus, the surveying instrument is easy to operate, and further unintentional operation such as pushing of wrong buttons and/or unintentional turning of the telescope can be prevented.
Optionally, the supporting member may allow vertical rotation and/or horizontal rotation of the telescope.
Further optionally, the movement detection system may detect a moving speed of the telescope, the moving speed being defined as a moving amount within a predetermined unit period.
Thus, it is possible to determine whether the telescope is quickly moved for a rough sighting or slowly moved for a fine sighting can be determined based on the detected moving speed. The moving speed may be detected with use of an encoder, as an amount of movement or rotation of the telescope within a unit period. Such an amount represents an angular speed or rotation speed of the telescope. Alternatively, it may also be possible to use a device for directly measuring the angular speed or the rotation speed.
It is possible that the controlling system categorizes moving speeds of the telescope into a plurality of ranges, and determines a range where the detected moving speed is included, and that the controlling system controls the auto-focusing system in accordance with the range where the detected moving speed is included.
In this case, the plurality of ranges may include first, second and third ranges, a moving speed included in the first range being slower than that included in the second range, a moving speed included in the second range being slower than that included in the third range, and wherein the controlling system controls the auto-focusing system to perform the auto-focusing operation whenever the moving speed detected by the detecting system is included in the second range.
Optionally, the controlling system may control the auto-focusing system to perform the auto-focusing operation by a predetermined times when a previously detected moving speed is included in the second range or third range, and a currently detected moving speed is included in the first range.
With this constitution, the power consumption of the auto-focusing system is reduced in comparison with a case where the auto-focusing system operates continuously, since the auto-focusing operation is performed only when it is necessary.
Alternatively or optionally, the plurality of ranges may include first, second, and third ranges, a moving speed included in the first range being slower than that included in the second range, a moving speed included in the second range being slower than that included in the third range, and the controlling system may control the auto-focusing system to perform the auto-focusing operation intermittently while the moving speed is included in the second range.
In this case, the frequency of the auto-focusing operations, which are performed while the moving speed is included in the second range, is greater as the moving speed is slower.
Further optionally, the second range may be divided into a first sub-range and a second sub-range. In this case, a first or a second frequency is selected depending on whether the moving speed is included in the first sub-range or the second sub-range.
Alternatively, the moving speed of the telescope may be divided into a first and a second ranges, a moving speed included in the first range being slower than that included in the second range, and the controlling system controls the auto-focusing system to perform the auto-focusing operation only when the moving speed is included in the first range. In this case, only one threshold value is referred to.
According to another aspect of the invention, there is provided a surveying instrument, which includes: a telescope utilized for sighting at an aiming point; an auto-focusing system that performs an auto-focusing operation for automatically adjusting focusing condition of the telescope; a supporting member that movably supports the telescope; a movement detection system that detects, based on a movement of the telescope, a moving status of the telescope, the moving status including a rough sighting status, a fine sighting status, and a suspended status; and a controlling system that controls the auto-focusing system to perform the auto-focusing operation in accordance with the moving status detected by the movement detection system.
Optionally, the controlling system may allow the auto-focusing system to perform the auto-focusing operation when the moving status of the telescope is the fine sighting status, while inhibit the auto-focusing system from performing the auto-focusing operation when the moving status of the telescope is the rough sighting status.
Further optionally, the controlling system may control the auto-focusing system to perform the auto-focusing operation immediately when the moving status of the telescope has changed to the suspended status, and inhibit the auto-focusing operation thereafter, until the moving status of the telescope is changed to the fine sighting status.
Since the auto-focusing system is controlled in accordance with the moving status of the telescope, the auto-focusing operation is executed only when it is necessary, and is not executed when it is unnecessary. Accordingly, operability of the surveying device is improved.
Further optionally, the controlling system may control the auto-focusing system to perform the auto-focusing operation continuously or intermittently while the moving status of the telescope is the fine sighting status.
When the auto-focusing operations are executed intermittently, the frequency thereof may be determined to be greater as a moving speed of the telescope is faster.
Still optionally, the moving speed of the telescope, when the moving status of the telescope is the fine sighting status, may be divided into a plurality of ranges, and in this case, the frequency of the auto-focusing operations may vary in accordance with a range where the moving speed of the telescope is included.
It should be noted that the surveying instrument according to the invention may include a distance metering device and/or a device that detects horizontal and elevational angles between a reference point to an aiming point, with respect to a predetermined station.